CHROMAN DERIVATIVE

Abstract: 1. A chroman derivative represented by the following formula: wherein X represents H, -CH 2 OH, -CHO, -COOH, -COOCH 3 , -CH=NOH, - CONH 2 , -COCH 3 , -CH(OH)CH 3 , Br, or CN; Y represents a hydroxyl group which may optionally be protected; R represents an alkyl group, alkenyl group, or aralkyl group; provided that, where X is hydrogen atom, R is an alkyl group, alkenyl group, or aralkyl group each having 16 or more carbon atoms; and a vitamin E-like active medicament comprising said derivative as an active ingredient.

Description: Technical Field The present invention relates to novel chroman derivatives. The chroman derivatives of the present invention have vitamin E activities and antioxidation activity, and are useful as medicaments and ingredients of pharmaceutical composition and the like. Background Art Vitamin E is known to have various physiological activities such as anti-sterile activity, anti-amyotrophic activity, and anti-hemolytic activity. The physiological activities are considered to be based on its anti-oxidation activity. Tocopherol and tocotrienol, which are naturally occurring vitamin Es, are structurally characterized in that the benzene ring moiety of the chroman ring is substituted with methyl groups. Such vitamin E derivatives as tocopheramine (J. Am. Chem. Soc., 64, 1082-1084, 1942), tocopherothiol, and thio-tocopherol are known. All of these vitamin E derivatives have methyl groups at 5-, 7-, and 8-positions of the respective chroman rings. A vitamin E derivative having dihydrobenzofran ring, instead of the chroman ring, is also known. The compound also has methyl groups at 4-, 5-, and 7-positions of the dihydrobenzofrun ring, which corresponds to 5-, 6-, and 8-positions of the chroman ring, respectively. Each of the above-described compounds are reported to have vitamin E activities. Compounds introduced with a hydroxymethyl group or a formyl group at 5-position of a chroman ring (Chemiker-Zeitung, 115, pp. 113-116, 1991). However, no pharmacological activity of these compounds is described in the publication. The French Patent Application Fr-A-2,121,750 discloses a compound zeta 2 -tocopherol (5,7-dimethyl-tocol) having vitamin E-like properties. The European Patent Application 0 445 827 discloses various chroman derivatives (page 3 compound IV; page 10 compound IV-IB; page 18/19 formula IV-9; page 57 compound 58). Due to this document EP 0 445 827 the disclaimer in claim 1 of the present patent application has been introduced. However, those compounds are not known to have vitamin E-like properties. Disclosure of Invention The inventors of the present invention conducted molecular designs to provide vitamin E derivatives having excellent pharmacological activities. As a result of syntheses of various compounds, the inventors found that compounds having a chroman ring, in which a methyl group at 8-position is subjected to an oxidation derivatization or a methyl group at 8-positionn is replaced with a hydrogen atom, had various physiological activities including unique anti-oxidation activity and preventive activity against dysembryoplasia. The present invention was achieved on the basis of these findings. The present invention thus provides chroman derivatives represented by the following formula (I): wherein X represents -CH 2 OH, -CHO, -COOH, -COOCH 3 , -CH=NOH, -CONH 2 , -COCH 3 , -CH(OH)CH 3 , Br, or CN; Y represents a hydroxyl group which may optionally have a protective group; R represents an alkyl group, alkenyl group, or aralkyl group; excluding the croman derivative wherein X is a -CHO group or -Br and R represent a -CH 3 group. The disclaimer has been introduced due to EP 0 445 827. According to an embodiment of the present invention, the chroman derivatives wherein Y is a non-protected hydroxyl group are provided. According to other embodiments of the present invention, there are provided a vitamin E-like active medicament comprising the chroman derivative as an active ingredient; the vitamin E-like active medicament used for therapeutic and preventive treatments of sterility; the vitamin E-like active medicament used for therapeutic and preventive treatments of ischemic disorders; the vitamin E-like active medicament used for therapeutic and preventive treatments of arterial sclerosis; the vitamin E-like active medicament used for activation of microcirculation; the vitamin E-like active medicament used for prevention of fetal abnormality; and the chroman derivatives used as antioxidants. Best Mode for Carrying Out the Invention In the above formula (I), examples of the alkyl groups represented by R include straight- or branched-chain lower or middle alkyl groups. Examples of the lower alkyl group include straight- or branched-chain alkyl groups having 1 to 5 carbon atoms such as, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, and neopentyl groups. As the middle alkyl group, for example, straight- or branched-chain middle alkyl groups having 6 to about 22 carbon atoms may be used. As the aralkyl group, such groups may be used in which the above-mentioned alkyl groups substituted, preferably at their terminal methyl groups, with one or more phenyl groups. For example, benzyl group and phenethyl group may be used. Examples of the alkenyl group include those characterized by the above-mentioned alkyl groups introduced with one or more double bonds. Where a lower alkenyl group is used, the number of the unsaturated double bond may preferably be one. However, the position of the double bond is not particularly limited. For example, where an isopentenyl group is used, any one of isopentenyl groups, -CH=CHCH 2 CH(CH 3 ) 2 , -CH 2 CH=CHCH(CH 3 ) 2 , -CH 2 CH 2 CH=C(CH 3 ) 2 , or - CH 2 CH 2 CH 2 C ( CH 3 ) )=CH 2 may be used. Among the above isopentenyl groups, -CH 2 CH 2 CH=C(CH 3 ) 2 is preferably used. In addition, where middle alkenyl groups containing repeated isoprene units are used as the middle alkenyl groups, those groups comprising the isoprene repeating units -CH 2 CH 2 CH 2 CH(CH 3 ))- introduced with at least one double bond. The positions of the introduced double bonds are not particularly limited. For example, an alkenyl group represented by -[CH 2 CH 2 CH=C(CH 3 )]n-CH 3 (n represents an integer of from 1 to 4) is preferably used. Among the above-explained alkyl, alkenyl, and aralkyl groups represented by R, alkyl groups are preferably used, and most preferably, middle alkyl groups containing repeated isoprene units such as a group represented by -[(CH 2 CH 2 CH 2 CH(CH 3 )]n-CH 3 (n represents an integer of from 1 to 4) may be used. Where Y represents a hydroxyl group having a protective group, any one of hydroxyl protective groups known to those skilled in the art may be used as the protective groups. For example, benzyl, benzoyl, acetyl, trimethylsilyl group and the like may be used. Among the chroman derivatives of present invention, compounds where X is -CHO group may be prepared by reacting 5,7-dimethyltocopherol, which is prepared according to the method described below as a reference example, with HCN or trimethylsilyl cyanide (TMS-CN). Compounds where X is -CH 2 OH can be prepared by the reduction of the above formyl compounds. Compounds where X is -COOH can be prepared by treating 5,7-dimethyl-8-halo-tocopherol, which is obtained by halogenating the above-described dimethy compounds, with a strong base to prepare its anion, followed by reacting with CO 2 . In addition, compounds where X is an acyl group can be prepared by Friedel-Crafts acylation using 5,7-dimethyltocopherol as a starting material. The method for preparing the chroman derivatives of the present invention will be further detailed in the following examples. The chroman derivatives of the present invention have anti-oxidation activity and exhibit vitamin E-like physiological activities, pharmaceutical compositions comprising one or more of the above-mentioned compounds, as one or more active ingredients, are useful as vitamin E-like active medicaments. For example, the vitamin E-like active agents of the present invention are useful for therapeutic and preventive treatments of sterility, therapeutic and preventive treatments of ischemic disorders and arterial sclerosis, and activation of microcirculation. The route of administration of the vitamin E-like active medicament of the present invention is not particularly limited and they may be administered orally and parenterally. Examples of pharmaceutical formulations suitable for oral administrations include tablets, capsules, powders, fine granules, granules, liquids, and syrups. Examples of pharmaceutical formulations suitable for parenteral administrations include injections, suppositories, inhalants, ointments, and plasters. The vitamin E-like active medicaments of the present invention may be prepared by optionally adding pharmacologically and pharmaceutically acceptable additives. Example of the pharmacologically and pharmaceutically acceptable additives include excipients, disintegrators or disintegrating aids, binders, lubricants, coating agents, coloring agents, diluents, base materials, dissolving agents or dissolving accelerators, isotonizing agents, pH adjusting agents, stabilizers, propellants, tackifiers, and the like. Pharmaceutical additives, for example, excipients such as glucose, lactose, D-mannitol, starch, and crystalline cellulose; disintegrator or disintegrating aids such as carboxymethyl cellulose, starch, and carboxymethyl cellulose calcium; binders such as hydroxypropyl cellulose, hydroxypropylmethyl cellulose, polyvinylpyrrolidone, and gelatin; lubricants such as magnesium stearate and talc; coating agents such as hydroxypropylmethyl cellulose, saccharose, polyethylene glycol, and titanium oxide; bases such as vaseline, liquid paraffin, polyethylene glycol, gelatin, kaolin, glycerin, purified water, and hard fat; propellants such as fron gases, diethyl ether, and compressed gases; tackifiers such as sodium polyacrylate, polyvinyl alcohol, methyl cellulose, polyisobutylene, and polybutene; and base sheets such as cotton cloth and plastic sheets may be added to the pharmaceutical formulations suitable for oral administrations, and transdermal or transmucosal application. Pharmaceutical additives, for example, dissolving agents or dissolving accelerators such as distilled water for injection, physiological saline, and propylene glycol which can provide aqueous injections or injections prepared by dissolving before use; isotonizing agents such as glucose, sodium chloride, D-mannitol, and glycerin; and pH adjusting agents such as inorganic acids, organic acids, inorganic bases, and organic bases may be added to the pharmaceutical formulations suitable for injections. The dose of the vitamin E-like active medicaments of the present invention is not particularly limited, which may be suitably chosen depending on, for example, the routes of administrations, ages, body weights, and conditions of patients. For example, the medicament may be administered to an adult in an amount of 1 to 1,000 mg, preferably 1 to 100 mg per day for oral administration. The vitamin E-like active medicaments of the present invention may be administered once or several times a day. Periods of times for the administration may also be chosen depending on, for example, the ages and conditions of patients. The chroman derivatives of the present invention may also be used as antioxidants. For example, they can be used as antioxidants to prevent oxidation of various components contained in a variety of drugs, cosmetics, food and the like. For such purposes, amounts to be applied may suitably be chosen depending on the purposes, for example, according to an amount of tocopherol ordinarily used in drugs, cosmetics, or food as an antioxidant. When used as antioxidants such as those for drugs or cosmetics, the antioxidants of the present invention may be used in an amount of from 0.1 to 10 mg, for example, based on 1 g of main components. Examples The present invention will be further detailed by examples. However, the scope of the present invention is not limited to these examples. Those Examples definded as reference examples do not lie within the scope of claim 1. Example 1 (reference) A mixture of 2,6-dimethylhydroquinone (772 mg, 5.59 mmol), ZnCl 2 (332 mg, 2.80 mmol, 0.5 eq.), silica gel (777 mg), concentrated hydrochloric acid (4 drops), and carbon tetrachloride (8 ml) was refluxed under argon flow. A solution of CH 2 =CHC( CH 3 ) 2 OH (568 mg, 6.59mmol, 1.2 eq.) in carbon tetrachloride (6 ml) was added dropwise to the mixture over 20 minutes. Then, the mixture was further stirred for 80 minutes at an outer temperature of 110°C. After cooling to room temperature, the reaction mixture was added with dichloromethane (200 ml) and filtered. The filtrate was successively washed with a mixture of 5% NaOH and 1% Na 2 S 2 O 4 (90 ml), water (90 ml), and brine (100 ml). The organic layer was dried over MgSO 4 and filtered, and then the solvent was evaporated to give a crude product (1.10 g). After purification by silica gel column chromatography (ethyl acetate:n-hexane = 1:5), 907 mg of the desired compound (the compound of formula I where R = CH 3 and X = H) was obtained (yield 79%). After recrystallization from n-hexane, colorless needles (m.p. 88 °C ) were obtained. 1 H-NMR (CDCl 3 , 60MHz): δ 1.28 (6H, s), 1.77 (2H, t, J=6Hz), 2.11 (3H, s), 2.17 (3H, s), 2.60 (2H, t, J=6Hz), 4.17 (1H, s), 6.48 (1H, s) IR (KBr): 3320, 2960, 2920 cm -1 Elemental analysis Calcd. N: 0, C: 75.69, H: 8.80 Found N: 0, C: 75.68, H: 8.92 Example 2 (reference) A mixture of 2,6-dimethylhydroquinone (415 mg, 3.00 mmol), ZnCl 2 (204 mg, 1.50 mmol, 0.5 eq.), silica gel (415 mg), concentrated hydrochloric acid (3 drops), and carbon tetrachloride (6 ml) was refluxed under argon flow. To this mixture, a solution of CH 3 CH(CH 3 )CH 2 CH 2 CH 2 C(CH 3 ) (OH)CH=CH 2 (582 mg, 3.72 mmol, 1.2 eq.) in carbon tetrachloride (3 ml) was added dropwise over 20 minutes, and the funnel was washed with carbon tetrachloride (1 ml). Then, the mixture was further stirred at an outer temperature of 115 °C for 1 hour. After cooling to room temperature, the reaction mixture was added with dichloromethane (180 ml) and filtered. The filtrate was successively washed with a mixture (90 ml) of 5% NaOH and 1% Na 2 S 2 O 4 , water (90 ml) , and brine (90 ml). After the organic layer was dried over MgSO 4 and filtered, the solvent was evaporated to give brown oil (943 mg). After purification by silica gel column chromatography (dichloromethane:n-hexane = 3:2), the desired compound (the compound of formula I where R = CH 2 CH 2 CH 2 CH(CH 3 ) 2 and X = H) was obtained as pale orange crystals (681 mg, yield 83 %). After recrystallization from n-hexane, white granule crystals were obtained (m.p. 46-47°C). 1 H-NMR (CDCl 3 , 400MHz): δ 0.86 (6H, d, J=6.6Hz), 1.23 (3H, s), 1.12-1.61 (7H, m), 1.72-1.87 (2H, m), 2.12 (3H, s), 2.18 (3H, s), 2.58 (2H, t, J=6.9Hz), 4.16 (1H, br.s), 6.47 (1H, s) Elemental analysis Calcd. N; 0, C; 78.21, H; 10.21 Found N; 0, C; 78.11, H; 10.29 Example 3 (reference) A mixture of 2,6-dimethylhydroquinone (1.50 g, 10.9 mmol), ZnCl 2 (739 mg, 5.43 mmol, 0.5 eq.), silica gel (1.50 g), concentrated hydrcchloric acid (0.5 ml), and carbon tetrachloride (21 ml) was refluxed under argon flow. To this mixture, a solution of CH 3 CH(CH 3 )CH 2 CH 2 CH 2 CH(CH 3 )CH 2 CH 2 CH 2 C(CH 3 )(OH)CH=CH 2 (2.96 g, 13.0 mmol, 1.2 eq.) in carbon tetrachloride (12 ml) was added dropwise over 25 minutes and the funnel was washed with carbon tetrachloride (3 ml). Then, the mixture was further stirred at an outer temperature of 115°C for 1 hour. After cooled to room temperature, the mixture was added with dichloromethane (500 ml) and filtered. The filtrate was successively washed with a mixture (200 ml) of 5% NaOH and 1% Na 2 S 2 O 4 , water (200 ml) and brine (200 ml). After the organic layer was dried over MgSO 4 and filtered, the solvent was evaporated to give oil (4.46 g). After purification by silica gel column chromatography (dichloromethane:n-hexane = 1:1, the desired compound (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 and X = H) was obtained as yellow oil (3.17 g, yield 84 %). 1 H-NMR (CDCl 3 , 400MHz): δ 0.84 (3H, d, J=6.6Hz), 0.86 (6H, d, J=6.6Hz), 1.23 (3H, s), 1.00-1.60 (14H, m), 1.71-1.87 (2H, m), 2.12 (3H, s), 2.18 (3H,s), 2.58 (2H, t, J=6.2Hz), 4.15 (1H, s), 6.48 (1H, s) Example 4 (reference) A mixture of 2,6-dimethylhydroquinone (1.50 g, 10.9 mmol), ZnCl 2 (743 mg, 5.45 mmol, 0.5 eq.), silica gel (1.50 g), concentrated hydrochloric acid (0.5 ml), and carbon tetrachloride (20 ml) was refluxed under argon flow. To this mixture, a solution of isophytol (3.88 g, 13.1 mmol, 1.2 eq.) in carbon tetrachloride (10 ml) was added dropwise over 30 minutes. The mixture was then stirred at an outer temperature of 110°C for 1 hour. After cooling to room temperature, the reaction mixture was added with dichloromethane and filtered. The dichloromethane layer was successively washed with a mixture of 5% NaOH and 1% Na 2 S 2 O 4 , water, and brine. The organic layer was dried over MgSO 4 and filtered, and the solvent was evaporated under reduced pressure to give brown oil (5.46 g). After purification by silica gel chromatography (dichloromethane:n-hexane = 9:10), the desired compound (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 )] 3 -CH 3 and X = H) was obtained as colorless oil (2.80 g, yield 62 %). 1 H-NMR (CDCl 3 , 400MHz): δ 0.83-0.87 (12H, m), 1.23 (3H, s), 1.00-1.62 (21H, m), 1.71-1.87 (2H, m), 2.12 (3H, s), 2.18 (3H, s), 2.58 (2H, t, J=6.9Hz), 4.15 (1H, s), 6.47 (3H, s) Example 5 (reference) The compound of Example 1 (300 mg) was dissolved in trifluoroacetic acid (10.0 ml), trifluoromethane-sulfonic acid (0.19 ml) was added to the solution under ice-cooling, and then TMS-CN (1.0 ml) under ice cooling, followed by twice addition of TMS-CN with 2 hour interval. After the mixture was allowed to react at room temperature for 24 hours in total, the reaction solution was poured into ice water to carry out hydrolysis, and then the mixture was extracted with dichloromethane. The organic layer was washed with saturated aqueous sodium hydrogen carbonate, dried over MgSO 4 and filtered. The filtrate was concentrated under reduced pressure and the residue obtained was purified by silica gel column chromatography. The resulting product (the compound of formula I where R = CH 3 and X = CHO) was recrystallized from benzene/n-hexane to give yellow columnar crystals. m.p. 131-133°C. 1 H-NMR (CDCl 3 , 400MHz): δ 1.34 (6H, s), 1.85 (2H, t, J=6.6Hz), 2.19 (3H, s), 2.48 (3H, s), 2.66 (2H, t, J=6.6Hz), 4.60 (1H, br), 10.58 (1H, s) IR (KBr): 3360, 2960, 2920, 1650, 1600 cm -1 M + 234 Elemental analysis Calcd. N; 0, C; 71.77, H; 7.74 Found N; 0, C; 71.86, H; 7.85 Examples 6 to 8 Using the compounds of Examples 2 to 4, compounds of Examples 6 to 8 were obtained in the same manner as Example 5. Compound of Example 6 (the compound of formula I where R = CH 2 CH 2 CH 2 CH(CH 3 ) 2 and X = CHO) Yellow oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.86 (6H, d, J=6.6Hz), 1.28 (3H, s), 1.10-1.68 (7H, m), 1.78-1.93 (2H, m), 2.19 (3H, s), 2.48 (3H, s), 2.64 (2H, t, J=7.0Hz), 4.44 (1H, s), 10.58 (1H, s) Compound of Example 7 (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 and X = CHO) Yellow oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.85 (3H, d, J=6.9Hz), 0.86 (3H, d, J=6.6Hz) ,1.28 (3H, s) 1.00-1.68 (14H, m), 1.78-1.92 (2H, m), 2.19 (3H, s), 2.48 (3H, s), 2.64 (2H, t, J=6.6Hz), 4.40 (1H, br.s), 10.58 (1H, s) Compound of Example 8 (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 and X = CHO) Pale yellow oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.85 (12H, m), 1.00-1.69 (21H, m), 1.28 (3H, s), 1.77-1.92 (2H, m), 2.19 (3H, s), 2.48 (3H, s), 2.64 (2H, t, J=6.6Hz), 4.56 (1H, br.s), 10.58 (1H, s) Example 9 The compound of Example 5 (100 mg, 0.43 mmol) was dissolved in methanol (3 ml) and stirred on an ice bath. To this solution, an ice cooled solution of NaBH 4 (22 mg, 0.57 mmol, 1.3 eq.) in methanol (2 ml) was added dropwise and mixed over 5 minutes under an ice bath. After removing the ice bath, the solution was stirred for 10 minutes at room temperature, and then the reaction was stopped by adding water (5 ml). The methanol was evaporated under reduced pressure, and the residue was extracted with dichloromethane. The organic layer was dried over MgSO 4 and filtered, and the solvent was evaporated under reduced pressure to give the desired compound (the compound of formula I where R = CH 3 and X = CH 2 OH) as white powder (98 mg, yield 96 %). Recrystallization from benzene/n-hexane gave white powder crystals (m.p. 125 °C ). 1 H-NMR (CDCl 3 , 400MHz): δ 1.32 (6H, s), 1.83 (2H, t, J=6.6Hz), 2.13 (3H, s), 2.25 (3H, s), 2.56 (1H, br), 2.64 (2H, t, J=6.6Hz), 4.26 (1H, s), 4.70 (2H, br.s) IR (KBr): 3410, 3250, 2960, 2920 cm -1 Elemental analysis Calcd. N; 0, C; 71.16, H; 8.53 Found N; 0, C; 71.38, H; 8.68 Examples 10 to 12 Using the compounds of Examples 6 to 8, compounds of Examples 10 to 12 were obtained in the same manner as Example 9. Compound of Example 10 (the compound of formula I where R = CH 2 CH 2 CH 2 CH(CH 3 ) 2 and X = CH 2 OH) Colorless oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.87 (6H, d, J=6.6Hz), 1.12-1.65 (7H, m), 1.26 (3H, s), 1.75-1.90 (2H, m), 2.13 (3H, s), 2.23 (3H, s), 2.61 (2H, t, J=7.0Hz), 4.49 (1H, br), 4.70 (2H, br.t) Compound of Example 11 (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 and X = CH 2 OH) Colorless oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.85 (3H, d, J=5.5Hz), 0.86 (6H, d, J=6.6Hz), 1.26 (3H, s), 1.01-1.66 (14H, m), 1.74-1.91 (2H, m), 2.13 (3H, s), 2.25 (3H, s), 2.62 (2H, t, J=6.9Hz), 4.25 (1H, br.s), 4.68 (1H, d, J=12.0Hz), 4.72 (1H, d, J=12.0Hz) Compound of Example 12 (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 ] 3 CH 3 and X = CH 2 OH) Colorless oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.83-0.88 (12H, m), 1.00-1.67 (21H, m), 1.26 (3H, s), 1.77-1.92 (2H, m), 2.13 (3H, s), 2.25 (3H, s), 2.62(2H, T, J=6.9Hz), 4.25 (1H, br.s), 4.68 (1H, d, J=12.0Hz), 4.72 (1H, d, J=12.0Hz) Example 13 (reference) 60% NaH (462 mg, 11.5 mmol, 1.2 eq.) was washed several times with n-hexane and suspended in dimethylformamide. A solution of the compound of Example 1 (2.0 g, 9.7 mmol) in dimethylformamide (1.5 ml) was added dropwise to the suspension over 5 minutes with stirringon an ice bath. After completion of the dropwise addition, stirring was continued for 10 minutes, and then benzyl bromide (2.1 g, 12.1 mmol, 1.3 eq.) in dimethylformamide (10 ml) was added. After stirring for 1 hour on an ice bath, the reaction was stopped by adding water. The mixture was extracted with dichloromethane and dried over MgSO 4 , the solvent was evaporated. Purification by silica gel column chromatography (dichloromethane:n-hexane = 2:3) gave the compound where 6-hydroxyl group of the compound of Example 1 was benzylated (2.9 g, yield 88 %). Colorless oil 1 H-NMR (CDCl 3 , 400MHz): δ 1.31 (6H, s), 1.81 (2H, t, J=7.0Hz), 2.18 (3H, s), 2.25 (3H, s), 2.60 (2H, t, 7.0Hz), 4.73 (2H, s), 6.51 (1H, s), 7.34 (1H, t, 7.3Hz), 7.42 (2H, t, 7.3Hz), 7.49 (2H, d, J=7.3 Hz) Examples 14 to 16 By the benzylation of respective 6-hydroxyl groups of the compounds of Examples 2 to 4 in the same manner as Example 13, compounds of Examples 14 to 16 were prepared. Compound of Example 14 (reference) Colorless oil 1 H-NMR ( CDCl 3 , 400MHz): δ 0.37 (6H, d, 6.6Hz), 1.25 (3H, s), 1.14-1.63 (7H, m), 1.73-1.89 (2H, m), 2.25 (3H, s), 2.58 (2H, t, 7.0Hz), 4.73 (2H, s), 6.51 (1H, s), 7.34 (1H, t, 7.3Hz), 7.42 (2H, t, 7.3Hz), 7.49 (2H, d, J=7.3 Hz) Compound of Example 15 (reference) Colorless oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.84 (3H, d, 6.6Hz), 0.86 (6H, d, 6.6Hz), 1.25 (3H, s), 1.00-1.63 (14H, m), 1.72-1.89 (2H, m), 2.17 (3H, s), 2.24 (3H, s), 2.57 (2H, t, 7.0Hz), 4.73 (2H, s), 6.51 (1H, s), 7.34 (1H, t, 7.3Hz), 7.42 (2H, t, 7.3Hz), 7.49 (2H, d, J=7.3 Hz) Compound of Example 16 (reference) Colorless oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.83-0.87 (12H, m), 1.25 (3H, s), 1.00-1.62 (21H, m), 1.71-1.87 (2H, m), 2.17 (3H, s), 2.24 (3H, s), 2.57 (2H, t, 7.0Hz), 4.73 (2H, s), 6.51 (1H, s), 7.34 (1H, t, 7.3Hz), 7.42 (2H, t, 7.3Hz), 7.49 (2H, d, J=7.3 Hz) Example 17 (reference) A solution of the compound of Example 13 (1.00 g, 3.37mmol) in carbon tetrachloride (6 ml) was added to CF 3 CO 2 Ag (745 mg, 3.37 mmol, 1.0 eq.). A solution of Br 2 (0.32 ml, 3.37 mmol, 1.0 eq.) in carbon tetrachloride (6 ml) was added dropwise to the mixture with stirring. After additional stirring for 30 minutes, the reaction mixture was filtered and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel column chromatography (dichloromethane:n-hexane = 2:3) to give 8-bromo compound (820 mg, yield 65 %). 1 H-NMR (CDCl 3 , 400MHz): δ 1.34 (6H, s), 1.79 (2H, t, J=7.0Hz), 2.14 (3H, s), 2.37 (3H, s), 2.60 (2H, t, J=7.0Hz), 4.68 (2H, s), 7.32 (1H, t, J=7.3Hz), 7.38 (2H, t, J=7.3Hz), 7.46 (2H, d, J=7.3Hz) Example 18 A solution of the compound of Example 17 (100 mg, 0.27 mmol) in absolute ether (2.5 ml) was added to 14% n-BuLi (in 0.17 ml of n-hexane, 0.37 mmol, 1.4 eq.). The reaction mixture was stirred for 45 minutes on a dry ice-acetone bath (-70 °C ) and then poured to dry ice. After acidification with aqueous 2N HCl, the mixture was extracted with ethyl acetate and washed with brine and water. The organic layer was dehydrated over MgSO 4 , and the solvent was evaporated under reduced pressure to give a crude product (95 mg). The product was purified by silica gel column chromatography (dichloromethane/n-hexane = 2:3→ dichloromethane/ethyl acetate/acetic acid = 100:100:1) to give 8-carboxyl compound (46 mg, yield 50 %) and the recovered starting material (25 mg, 25 %). 1 H-NMR (CDCl 3 , 400MHz): δ 1.42 (6H, s), 1.93 (2H, t, J=6.7Hz), 2.23 (3H, s), 2.58 (3H, s), 2.68 (2H, t, J=6.7Hz), 4.70 (2H, s), 7.36 (1H, t, J=7.3Hz), 7.42 (2H, t, J=7.3Hz), 7.48 (2H, d, J=7.3Hz), 10.05 (1H, br) Example 19 The compound of Example 18 (200 mg, 0.59 mmol) was subjected to catalytic reduction in ethanol (80 ml) in the presence of 50 mg of Pd (10% carbon) at room temperature for 1 hour. The Pd-C was removed by filtration of the reaction mixture, and the solvent was evaporated under reduced pressure to give 149 mg of the desired compound (the compound of formula I where R = CH 3 and X = COOH). Recrystallization from ethanol/benzene gave colorless crystals. m.p. 174.5-176 °C. 1 H-NMR (CD 3 OD, 400MHz): δ 1.26 (6H, s), 1.81 (2H, t, J=6.6Hz), 2.12 (3H, s), 2.15 (3H, s), 2.63 (2H, t, J=6.6Hz) Elemental analysis Calcd. N; 0, C; 67.18, H; 7.25 Found N; 0, C; 66.90, H; 7.26 Examples 20 to 22 By the bromination of the compounds of Examples 14 to 16 in the same manner as Example 17, compounds of Examples 20 to 22 were obtained. Compound of Example 20 Orange oil 1 H-NMR (CDCl 3 , 400MHz) δ 0.88 (6H, d, 6.6Hz), 1.29 (3H, s), 1.13-1.68 (7H, m), 1.76-1.89 (2H, m), 2.15 (3H, s), 2.38 (3H, s), 2.61 (2H, t, J=7.0Hz), 4.70 (2H, s), 7.34 (1H, t, J=7.3Hz), 7.42 (2H, t, J=7.3Hz), 7.49 (2H, d, J=7.3Hz) Compound of Example 21 Orange oil 1 H-NMR (CDCl 3 , 400MHz) δ 0.84 (3H, d, 6.6Hz), 0.86 (6H, d, 6.6Hz), 1.29 (3H, s), 1.03-1.68 (14H, m), 1.77-1.90 (2H, s), 2.15 (3H, s), 2.38 (3H, s), 2.61 (2H, t, J=7.0Hz), 4.70 (2H, s), 7.34 (1H, t, J=7.3Hz), 7.42 (2H, t, J=7.3Hz), 7.49 (2H, d, J=7.3Hz) Compound of Example 22 Orange oil 1 H-NMR (CDCl 3 , 400MHz) δ 0.83-0.87 (12H, m), 1.00-1.70 (21H, m), 1.29 (3H, s), 1.75-1.90 (2H, m), 2.15 (3H, s), 2.37 (3H, s) 2.61 (2H, t, J=7.0Hz), 4.70 (2H, s), 7.34 (1H, t, J=7.3Hz) 7.42 (2H, t, J=7.3Hz), 7.49 (2H, d, J=7.3Hz) Examples 23 and 24 Compound of Example 23 and its des-benzyl compound, i.e., compound of Example 24 (Y = OH, R = CH 2 CH 2 CH 2 CH(CH 3 )CH 3 , X = COOH), were obtained from the compound of Example 20 in the same manners as Examples 18 and 19. Compound of Example 23 1 H-NMR (CDCl 3 , 400MHz) δ 0.87 (6H, d, 6.6Hz), 1.18 (2H, q. 14.8, 7.1Hz), 1.34 (3H, s), 1.35-1.70 (6H, m), 1.83-1.97 (2H, m), 2.21 (3H, s), 2.51 (3H, s), 2.64 (2H, t, J=6.6Hz), 4.70 (1H, s), 7.37 (1H, t, J=7.1Hz), 7.41 (2H, t, J=7.2Hz), 7.48 (2H, d, J=7.2Hz) Compound of Example 24 Colorless needles m.p. 125-126°C (dichloromethane/n-hexane) 1 H-NMR (CD 3 OD, 400MHz): δ 0.86 (6H, d, J=9.1Hz), 1.16 (2H, q, J=15.4, 7.7Hz), 1.32 (3H, s), 1.35-1.43 (2H, m), 1.50-1.69 (3H, m), 1.82-1.95 (2H, m), 2.17 (3H, s), 2.44 (3H, s), 2.65 (2H, t, 7.2Hz) Elemental analysis Calcd. N; 0, C; 71.22, H; 8.81 Found N; 0, C; 71.04, H; 8.84 Examples 25 and 26 Compound of Example 25 and its des-benzyl compound, i.e., compound of Example 26 (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 , X = COOH), were obtained from the compound of Example 21 in the same manners as Examples 18 and 19. Compound of Example 25 1 H-NMR (CDCl 3 , 400MHz) δ 0.84-0.87 (9H, m), 1.35 (3H, s), 1.08-1.66 (14H, m), 1.86-1.95 (2H, m), 2.21 (3H, s), 2.55 (3H, s), 2.65 (2H, t, J=6.5Hz), 4.70 (1H, s), 7.37 (1H, t, J=6.9Hz), 7.41 (2H, t, J=7.0Hz), 7.48 (2H, t, J=7.0Hz) Compound of Example 26 Colorless Oil 1 H-NMR (CD 3 OD, 400MHz): δ 0.83-0.86 (9H, m), 1.32 (3H, s), 1.12-1.66 (13H, m), 1.85-1.92 (2H, m), 2.18 (3H, s), 2.45 (3H, s), 2.65 (2H, t, 7.2Hz) Examples 27 and 28 Compound of Example 27 and its des-benzyl compound, i.e., compound of Example 28 (the compound of formula I where R = [CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 , X = COOH), were obtained from the compound of Example 22 in the same manners as Examples 18 and 19. Compound of Example 27 Colorless oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.83-0.87 (12H, m), 1.32 (3H, s), 1.00-1.74 (21H, m), 1.84-1.98 (2H, m), 2.22 (3H, s), 2.54 (3H, s), 2.64 (2H, t, J=7.0Hz), 4.70 (2H, s), 7.33 (1H, t, J=7.3Hz) 7.42 (2H, t, J=7.3Hz), 7.48 (2H, d, J=7.3Hz) Compound of Example 28 Pale yellow oil 1 H-NMR (CDCl 3 , 400MHz): δ 0.83-0.87 (12H, m), 1.34 (3H, s), 1.00-1.72 (21H, m), 1.83-1.98 (2H, m), 2.19 (3H, s), 2.50 (3H, s), 2.67 (2H, t, J=7.0Hz), 4.60 (1H, br.s) Example 29 ZnCl 2 (763 mg, 5.60 mmol) was suspended in 1,2-dichloroethane (3 ml). To this suspension, a solution of CH 3 COCl (243 mg, 3.09 mmol) in 1,2-dichloroethane (1.5 ml) was added dropwise and mixed at 0 °C. A solution of the compound of Example 1 (238 mg, 1.15 mmol) in 1,2-dichloroethane (2 ml) were added dropwise to the mixture at 0 °C and mixed. The mixture was stirred at room temperature for 2 hours and then a solution of CH 3 COCl (97 mg, 1.23 mmol) in 1,2-dichloroethane (1.5 ml) was added dropwise to the mixture and mixed at room temperature. The mixture was further stirred at room temperature for 1 hour and then poured into ice water (70 ml). The mixture was extracted 3 times with dichloromethane (each 40 ml), and the dichloromethane layer was washed with water until it became neutral, and then further washed with brine. The organic layer was dried over MgSO 4 and filtered. Then, the solvent was evaporated under reduced pressure to give the compound where a hydroxyl group at 6-position and chroman ring at 8-position were acetylated (337 mg). Purification by silica gel column chromatography (dichloromethane:n-hexane = 2:1) gave a purified product (199 mg, yield 59 %). Further recrystallization from dichloromethane/n-hexane /n-hexane gave colorless granular crystals (m.p. 96 °C). 1 H-NMR (CDCl 3 , 400MHz): δ 1.31 (6H, s), 1.82 (2H, t, J=6.9Hz), 1.98 (3H, s), 2.01 (3H, s), 2.38 (3H, s), 2.47 (3H, s), 2.62 (2H, t, J=6.9Hz) IR (KBr): 2960, 2920, 1760, 1690 cm -1 Elemental analysis Calcd. N; 0, C; 70.32, H; 7.64 Found N; 0, C; 70.43, H; 7.68 Example 30 The above-described compound (52 mg, 0.18 mmol) was dissolved in methanol (2 ml), and an aqueous 2N KOH (0.13 ml, 0.26 mmol, 1.4 eq.) was added, and then the mixture was stirred at room temperature for 1 hour. Methanol was evaporated under reduced pressure and water (5 ml) was added to the residue. 2N HCl (10 ml) was added so as to adjust its pH to 2, and the mixture was extracted 3 times with dichloromethane (each 10 ml). The organic layers were combined and washed with water (10 ml), dried over MgSO 4 , and then the solvent was evaporated under reduced pressure to give 44 mg (yield 98 %) of the desired compounds (the compound of formula I where R =CH 3 and X = COCH 3 ). Recrystallization from n-hexane gave colorless needles (m.p. 108°C). 1 H-NMR (CDCl 3 , 400MHz): δ 1.30 (6H, s), 1.81 (2H, t, J=6.9Hz), 2.10 (3H, s), 2.13 (3H, s), 2.47 (3H, s), 2.63 (2H, t, J=6.9Hz), 4.37 (1H, br) Elemental analysis Calcd. N; 0, C; 72.55, H; 8.12 Found N; 0, C; 72.59, H; 8.24 Example 31 LiAlH 4 (10 mg, 0.24 mmol, 2 eq.) was suspended in absolute ether (1 ml) on an ice bath. A solution of the compound of Example 30 (30 mg, 0.12 mmol) in absolute ether (1 ml) was added dropwise to the suspension. The mixture was stirred for 1 hour on the ice bath and additional 1 hour at room temperature. The reaction was stopped by adding water to the reaction mixture, and the mixture was extracted with ether. The extract was dried over MgSO 4 and filtered, and then the solvent was evaporated under reduced pressure to give 35 mg of the desired compound (the compound of formula I where R = CH 3 and X = CH(OH)CH 3 ) as white crystals. The crystals were recrystallized from ethyl acetate/n-hexane to give 20 mg of colorless columnar crystals (yield 66 %, m.p. 134-135°C). 1 H-NMR (CDCl 3 , 400MHz): δ 1.34 (3H, s), 1.38 (3H, s), 1.50 (3H, d, J=6.6Hz), 1.84 (2H, t, J=6.6Hz), 2.11 (3H, s), 2.14 (3H, s), 2.64 (2H, t, J=6.6Hz), 4.44 (1H, br.s), 4.56 (1H, br.d, J=10.6Hz), 5.00 (1H, br.s) Elemental analysis Calcd. N; 0, C; 71.97, H; 8.86 Found N; 0, C; 72.24, H; 8.97 Example 32 (reference) NaH (80 mg, 60% oil dispersion) was washed with n-hexane 3 times, suspended in dimethylformamide (5 ml), and stirred under ice cooling. A solution of the compound of Example 5 (the compound of formula I where R = CH 3 and X = CHO, 400 mg, 1.68 mmol) in dimethylformamide (6 ml) was added dropwise to the mixture and stirred for 10 minutes. Then, a solution of benzyl bromide (360 mg, 2.10 mmol, 1.2 eq.) in dimethylformamide (6 ml) was added dropwise to the mixture. The mixture was stirred for 40 minutes on an ice bath and the reaction was stopped by adding water (2 ml). The mixture was extracted with dichloromethane, and the organic layer was dried over MgSO 4 , and then the solvent was evaporated to give the compound where the hydroxyl group at 6-position was protected by benzyl group (643 mg). The product was purified by silica gel column chromatography (dichloromethane:n-hexane = 3:2) to give the desired compound (536 mg, yield 98 %). Recrystallization from ethyl acetate/n-hexane gave cream diamondoid crystals (m.p. 61.5-62°C). 1 H-NMR (CDCl 3 , 400MHz): δ 6 1.36 (6H, s), 1.87 (2H, t, 7.0Hz), 2.23 (3H, s), 2.53 (3H, s), 2.64 (2H, t, J=7.0Hz), 4.69 (2H, s), 7.36 (1H, d, J=7.0Hz), 7.41 (2H, t, J=7.0Hz), 7.48 (2H, d, J=7.0Hz) Example 33 The compound of the above-described Example 32 was dissolved in methanol (2.5 ml) and added with an aqueous solution (1.5 ml) of hydroxylamine hydrochloride (222 mg, 3.2 mmol, 1.10 eq.). The mixture was heated at an outer temperature of 90°C for 3 hours and 20 minutes, and then, the reaction mixture was acidified by adding dry ice and extracted with dichloromethane. The organic layer was dried over Na 2 SO 4 and the solvent was evaporated to give crystals of 8-oxime compound (106 mg, yield 98 %). Recrystallization from dichloromethane/n-hexane gave colorless prisms (m.p. 136 °C). 1 H-NMR (CDCl 3 , 400MHz): δ 1.32 (3H, s), 1.82 (2H, t, 6.9Hz), 2.20 (3H, s), 2.46 (3H, s), 2.62 (2H, t, J=6.9Hz), 4.71 (2H, s), 7.34 (1H, t, J=7.0Hz), 7.40 (2H, t, J=7.0Hz), 7.49 (2H, d, J=7.0Hz), 8.56 (1H, s) Example 34 The compound of the above-described Example 33 (8-oxime compound, 102 mg, 0.30 mmol) and acetic anhydride (61 mg, 0.60 mmol, 1.2 eq.) were heated for three and a half hours and the reaction mixture was then poured into water. The mixture was extracted with dichloromethane and the organic layer was washed with saturated aqueous NaHSO 4 solution. The mixture was dried over MgSO 4 and the solvent was evaporated to give orange crystals of 8-cyano compound (101 mg). Purification by silica gel column chromatography (dichloromethane:n-hexane = 3:2) gave 94 mg of the desired compound, and further recrystallization from n-hexane gave colorless needles (m.p. 94°C). 1 H-NMR (CDCl 3 , 400MHz): δ 1.37 (6H, s), 1.85 (2H, t, 6.9Hz), 2.21 (3H, s), 2.42 (3H, s), 2.60 (2H, t, J=6.9Hz), 4.72 (2H, s), 7.36 (1H, t, J=6.9Hz), 7.41 (2H, t, J=6.9Hz), 7.46 (2H, d, J=6.9Hz) IR (KBr): 2200 cm -1 Example 35 A mixture of the compound of the above-described Example 34 (8-cyano compound, 82 mg, 0.26 mmol), diethylene glycol (2.5 ml), 40% aqueous KOH solution (3.5 ml), and 18-crown-6 ether (206 mg, 0.78 mmol, 1.3 eq.) was stirred at an outer temperature of 135 °C for 2 days. The reaction mixture was neutralized using concentrated hydrochloric acid and extracted with dichloromethane. The organic layer was dried over MgSO 4 and the solvent was evaporated. The residue was purified by silica gel column chromatography (dichloromethane:n-hexane = 1:1→ ethyl acetate: dichloromethane = 1:5) to afford 8-amide compound as colorless crystals (73 mg, yield 83 %). 1 H-NMR (CDCl 3 , 400MHz): δ 1.32 (6H, s), 1.83 (2H, t, 7.2Hz), 2.18 (3H, s), 2.36 (3H, s), 2.62 (2H, t, J=7.2Hz), 4.70 (2H, s), 5.77 (1H, br, s), 5.94 (1H, br, s), 7.35 (1H, t, J=7.1Hz), 7.41 (2H, t, J=7.1Hz), 7.48 (2H, d, J=7.1Hz) Elemental analysis Calcd. N; 4.13, C; 74.31, H; 7.42 Found N; 4.41, C; 74.22, H; 7.46 Example 36 The compound of the above-described Example 35 (50 mg, 0.15 mmol) was dissolved in ethanol (25 ml) and subjected to catalytic hydrogenation reduction at room temperature for 1 hour in the presence of Pd-C catalyst (15 mg). Then, the catalyst was removed by filtration and the solvent was evaporated to give 37 mg of the desired compound (the compound of formula I where R= CH 3 and X=CONH 2 ) as colorless cotton-like crystals (ethyl acetate/n-hexane, m.p. 221°C). 1 H-NMR (CDCl 3 , 400MHz): δ 1.31 (6H, s), 1.85 (2H, t, 6.6Hz), 2.16 (3H, s), 2.21 (3H, s), 2.69 (2H, t, J=6.6Hz) IR (KBr): 3340, 3160, 3050, 2950, 2900, 1740, 1660, 1610 cm -1 The compounds obtained by the above-described examples are shown in Table 1 below. Compound No. X Y R Example 1 § -H -OH -CH 3 Example 2 § -H -OH -CH 2 CH 2 CH 2 CH(CH 3 ) 2 Example 3 § -H -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 Example 4 § -H -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 Example 5 § -CHO -OH -CH 3 Example 6 -CHO -OH -CH 2 CH 2 CH 2 CH(CH 3 ) 2 Example 7 -CHO -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 Example 8 -CHO -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 Example 9 -CH, OH -OH -CH 3 Example 10 -CH 2 OH -OH -CH 2 CH 2 CH 2 CH(CH 3 ) 2 Example 11 -CH 2 OH -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 Example 12 -CH 2 OH -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 Example 13 § -H -OCH 2 C 6 H 5 -CH 3 Example 14 § -H -OCH 2 C 6 H 5 -CH 2 CH 2 CH 2 CH(CH 3 ) 2 Example 15 § -H -OCH 2 C 6 H 5 -[CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 Example 16 § -H -OCH 2 C 6 H 5 -[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 Example 17 § -Br -OCH 2 C 6 H 5 -CH 3 Example 18 -COOH -OCH 2 C 6 H 5 -CH 3 Example 19 -COOH -OH -CH 3 Example 20 -Br -OCH 2 C 6 H 5 -CH 2 CH 2 CH 2 CH(CH 3 ) 2 Example 21 -Br -OCH 2 C 6 H 5 -[CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 Example 22 -Br -OCH 2 C 6 H 5 -[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 Example 23 -COOH -OCH 2 C 6 H 5 -CH 2 CH 2 CH 2 CH(CH 3 ) 2 Example 24 -COOH -OH -CH 2 CH 2 CH 2 CH(CH 3 ) 2 Example 25 -COOH -OCH 2 C 6 H 5 -[CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 Example 26 -COOH -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 2 CH 3 Example 27 -COOH -OCH 2 C 6 H 5 -[CH 2 CH 2 CH 2 CH ( CH 3 ) ] 3 CH 3 Example 28 -COOH -OH -[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 Example 29 -COCH 3 -OCOCH 3 -CH 3 Example 30 -COCH 3 -OH -CH 3 Example 31 -CH(OH)CH 3 -OH -CH 3 Example 32 § -CHO -OCH 2 C 6 H 5 -CH 3 Example 33 -CH=NHOH -OCH 2 C 6 H 5 -CH 3 Example 34 -CN -OCH 2 C 6 H 5 -CH 3 Example 35 -CONH 2 -OCH 2 C 6 H 5 -CH 3 Example 36 -CONH 2 -OH -CH 3 The examples marked with § are reference examples. Test Example 1 Antioxidation activities of the chroman derivatives of present invention were evaluated by measuring inhibitions against a radical-initiated oxidation of methyl linoleate (suppressions of the amount of oxygen consumption, E. Niki et al., J. Biol. Chem., 259, 4177-4182, 1984). Where R 0 represents the rate of oxygen consumption in the absence of an antioxidant (mol/l. min); R inh represents the rate of oxygen consumption with the addition of an antioxidant (mol/l. min); t inh represents the duration time of antioxidant activity (min); and M represents the concentration of antioxidant (= 60 µM), the following definitions were made: Antioxidation ratio = (R 0 - R inh )/R 0 Antioxidation activity = (antioxidation ratio × duration of antioxidation)/M = (R 0 - R inh ) t inh / R 0 · M The results are shown in Table 2 set out below. Compound Antioxidation ratio Duration time (min.) Antioxidation activlty Example 9 0.61 49 49.7 Example 12 0.58 49 47.4 Example 5§ 0.37 >82 >50.6 Example 8 0.36 >79 >47.4 Example 19 0.58 >100 >96.7 Example 28 0.55 >100 >91.7 Example 1 § 0.61 53 53.9 Example 4 § 0.61 53 53.9 Example 30 0.48 50 40.0 Example 36 0.32 >80 >42.7 α-tocopherol 0.71 43 50.9 blank 0 0 0 Test Example 2 Vitamin E activities of the chroman derivatives of the present invention were examined as follows. (1) Preparation of vitamin E deficiency pregnant mice Female Jcl:ICR mice (purchased from Nippon Crea Co.,Ltd) were made pregnant and 8 female mice were chosen from each of litters immediately after the birth. Where numbers of female mice did not reach to 8, male mice from the same litter were added up to the total of 8 mice so as to achieve the same lactation conditions. From the 21st day after the birth, only the female mice (F1 mice) were freely fed with vitamin E (VE) deficient feed (purchased from Oriental Yeast Co.,Ltd.). Those female mice fed with vitamin E deficient feed (9-week old) were crossed with newly purchased Jcl: ICR male mice. Pregnancy was determined from the presence or absence of a vaginal plug and the day when a vaginal plug was observed was defined as 0th day of pregnancy. The following experiments were carried out by using those pregnant mice. (2) Administration of drugs Vitamin E used as a control drug; and the following chroman derivatives of the present invention: the compound of reference Example 4 (X=H, Y=OH, and R=-[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 ); the compound of Example 12 (X=CH 2 OH, Y=OH, and R=-[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 ); and the compound of Example 28 (X=COOH, Y=OH, and R=-[CH 2 CH 2 CH 2 CH(CH 3 )] 3 CH 3 ) were used with lard (no addition of vitamin E, purchased from Oriental Yeast Co.,Ltd.) as medium. The test compounds were added to lard and dissolved by heating at about 40°C so as to achieve the doses of each of the test compounds being 5 mg/kg body weight and 10 mg/kg body weight. Body weights of the 0th day of pregnancy were used as body weights for determining the dosages. Administration volume was 0.1 ml per 10 g of body weight and administrations were carried out using oral feeding tubes for mice. The control groups, in which test drugs were not administered, were further divided into two groups, i.e., a group where the mice were administered only lard at an amount of 0.1 ml per 10 g of body weight and another group where the mice were administered with neither of drugs nor lard. The administration periods were up to from the 6th day through the 15th day of pregnancy depending on organogenetic periods of mouse embryos. In addition, a control group was further provided for comparison (1 group) where mice were fed with CE-2 (purchased from Japan Crea Co.,Ltd), a normal feed not deficient in vitamin E. The groups administered with drugs and the control groups are summarized below. Group No. of dams Feed Dosage (mg/Kg) A Control (Normal Feed) 16 CE-2 - B Control (Lard administration) 6 VE-deficient feed - C Control (No administration) 4 " - D Vitamin E Administration 8 " 5 E " 7 " 10 F Administration of Compound of Ex. 4(ref.) 8 " 5 G " 10 " 10 H Administration of Compound of Ex. 12 8 " 5 I " 8 " 10 J Administration of Compound of Ex. 28 8 " 5 K " 8 " 10 (3) Observation of fetuses and statistical analysis On the 18th day of pregnancy, the mice were anesthetized with ether and subjected to caesarean section to observe the inside condition of the uteri, and then numbers of implantation, numbers of placental remnant, numbers of absorbed embryo, numbers of alive fetus, and numbers of dead fetus were counted. The results are shown in Tables 4 and 5. In addition, for live fetuses, measurements of body weights, measurements of placental weights, and sex determinations were carried out, and then, the absence or presence of the occurence of physical abnormality were macroscopically examined and counted. The numerical data obtained (body weights and placental weights) were analyzed by t-test, and the frequency data (numbers of implantation, numbers of placental remnant, numbers of absorbed embryo, numbers of alive fetus, numbers of dead fetus, and numbers of the occurence of physical abnormality) were analyzed by chi-square test. In Tables 4 and 5, symbols "a" and "b" represent that significant differences, i.e., p < 0.05 and p< 0.01, respectively, were observed between the normal feed control groups and the lard-administered (VE deficient feed) control groups, and symbols "c" and "d" represent that significant differences, i.e., p< 0.05 and p< 0.01, respectively, were observed between the lard-administered (VE deficient feed) control groups and the drug-administered groups. As shown in the above tables, body weights of the fetuses and placental weights of the vitamin E deficient feed control groups were significantly decreased as compared to the normal feed control group, and the frequency of occurrences of physical abnormality was significantly high. In contrast to those vitamin E deficient control groups, body weights of fetuses and placental weight were recovered in both of the groups administered with vitamin E or the chroman derivatives of the present invention, and frequencies of occurrences of physical abnormality were also significantly decreased in almost all of the groups. Among them, the compound of Example 12 of the present invention exhibited higher activities than vitamin E. From the foregoing results, it is apparent that the chroman derivatives of the present invention have vitamin E-like physiological activities and are useful for prevention of fetal abnormality. Industrial Applicability The chroman derivatives of the present invention have antioxidation activity and exhibit vitamin E-like activities such as prevention of fetal abnormality, and thus they are useful as medicaments and antioxidants.

Claims: A chroman derivative represented by the following formula: wherein X represents -CH 2 OH, -CHO, -COOH, -COOCH 3 , -CH=NOH, -CONH 2 , -COCH 3 , -CH(OH)CH 3 , Br, or CN; Y represents a hydroxyl group which may optionally be protected; R represents an alkyl group, alkenyl group, or aralkyl group; excluding the chroman derivative wherein X is a -CHO group or -Br and R represents a -CH 3 group. A chroman derivative according to claim 1, wherein Y is an unprotected hydroxyl group. A vitamin E-like active medicament according to formula I of claim 1 wherein X, Y and R have the same meaning as in claim 1. Use of the chroman derivative according to claim 3 for the manufacture of a medicament for therapeutic and/or preventive treatment of sterility. Use of the chroman derivative according to claim 3 for the manufacture of a medicament for therapeutic and/or preventive treatment of ischemic disorders. Use of the chroman derivative according to claim 3 for the manufacture of a medicament for therapeutic and/or preventive treatments of arterial sclerosis. Use of the chroman derivative according to claim 3 for the manufacture of a medicament for activation of microcirculation. An antioxidant according to formula I of claim 1 wherein X, Y and R have the same meaning as in claim 1.

Inventors: AKAIKE MASASHI, SHUDO KOICHI, AKAIKE, MASASHI, SHUDO, KOICHI
Applicants: SHUDO KOICHI, SHUDO, KOICHI, PROF. DR.
Application year: 1994
Main classification: C07D311
IPC codes: A61P9, C09K15, A61P3, A61K31, A61P15, A61P13, C07D311